1. Field of the Invention
This invention relates generally to processing of ore and more particularly to processing excavated ore including sized ore portions and oversize ore portions.
2. Description of Related Art
Surface mining operations are generally employed to excavate an ore deposit that is found near the surface. Such ore deposits are usually covered by an overburden of rock, soil, and/or plant matter, which may be removed prior to commencing mining operations. The remaining ore deposit may then be excavated and transported to a plant for processing to remove commercially useful products. The ore deposit may comprise an oil sand deposit from which hydrocarbon products may be extracted, for example.
In general, excavated ore includes sized ore portions having a size suitable for processing and oversize ore portions that are too large for processing. The oversize ore portions may be discarded and/or crushed to produce sized ore.
In the example of an oil sand ore deposit, such as the Northern Alberta oil sands, the ore deposit comprises about 70 to about 90 percent by weight of mineral solids including sand and clay, about 1 to about 10 percent by weight of water, and a bitumen or oil film. The bitumen may be present in amounts ranging from a trace amount up to as much as 20 percent by weight. Due to the highly viscous nature of bitumen, when excavated some of the ore may remain as clumps of oversize ore that requires sizing to produce a sized ore feed suitable for processing. Due to the northerly geographic location of many oil sands deposits, the ore may also be frozen making sizing of the ore more difficult. Such processing may involve adding water to the ore feed to produce an oil sand slurry, for example.